How many millimeters equal 1 em?

1 em ≈ 4.23 mm (at 12pt default). So conversely, 1 mm ≈ 0.236 em. Remember: 6 em = 25.4 mm (1 inch).

My metric spec says 20 mm padding. What's that in em for CSS?

20 mm × 0.236 ≈ 4.72 em. Use padding: 4.72em in your CSS for responsive spacing based on metric specs.

I need to convert a 15 mm margin from a European design system to em values.

15 mm × 0.236 ≈ 3.54 em. Use this when adapting international metric design specs to web CSS.

Does this conversion work for all em bases?

No. This assumes 12pt (print standard). If your design uses 16pt base (web standard), the conversion changes. Always verify your system's em base.

Millimeter to Em Converter

Enter a value to instantly convert between typography units.

From

Precision4 dp

1 Millimeter = 0.2362 Em

Key Formulas

Point → Pica

pc = pt × 0.0833333

Point → Inch

in = pt × 0.0138889

Pica → Inch

in = pc × 0.166667

Millimeters are metric fixed measurements; ems are relative typographic units. Converting metric specs to responsive em-based web design is essential for international teams. At the 12pt default em (common in print), 1 millimeter equals about 0.236 ems.

Last reviewed: 2026-06-11 · see our methodology

Frequently Asked Questions

Real-World Examples

5 mm ≈ 1.18 em. Small metric measurement (0.5 cm) translates to just over 1 em in responsive web padding.

5 mm = 1.181 em

10 mm (1 cm) ≈ 2.36 em. Standard metric margin width converts to flexible web spacing.

10 mm = 2.362 em

25.4 mm (1 inch) = exactly 6 em. Reference point for converting metric specs to responsive design.

25.4 mm = 6 em

50 mm (5 cm) ≈ 11.8 em. Large margin in metric translates to generous spacing in responsive layouts.

50 mm = 11.811 em

points to picas points to type inches picas to type inches points to mm pixels to points ems to rems

Millimeter to Em Converter

Key Formulas

Frequently Asked Questions

Real-World Examples

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